Analysis, Design and Performance Evaluation of Optical Fiber potx

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Abstract ii

Analysis, Design and Performance Evaluation of Optical Fiber

Spectrum-Sliced WDM Systems

by

Vivek Arya

Dr. Ira Jacobs, Chairman

Electrical Engineering

ABSTRACT

This dissertation investigates the design and performance issues of a recently demonstrated technique,

termed as spectrum-slicing, for implementing wavelength-division-multiplexing (WDM) in optical

fiber systems. Conventional WDM systems employ laser diodes operating at discrete wavelengths as

carriers for the different data channels that are to be multiplexed. Spectrum-slicing provides an

attractive low-cost alternative to the use of multiple coherent lasers for such WDM applications by

utilizing spectral slices of a broadband noise source for the different data channels. The principal

broadband noise source considered is the amplified spontaneous emission (ASE) noise from an

optical amplifier. Each slice of the spectrum is actually a burst of noise that is modulated individually

for a high capacity WDM system. The stochastic nature of the broadband source gives rise to excess

intensity noise which results in a power penalty at the receiver. One way to minimize this penalty, as

proposed and analyzed for the first time in this work, is to use an optical preamplifier receiver.

It is shown that when an optical preamplifier receiver is used, there exists an optimum filter

bandwidth which optimizes the detection sensitivity (minimizes the average number of photons/bit) for

a given error probability. Moreover the evaluated detection sensitivity represents an order of

magnitude ( > 10 dB) improvement over conventional PIN receiver-based detection techniques for

such spectrum-sliced communication systems. The optimum is a consequence of signal energy

fluctuations dominating at low values of the signal time bandwidth product (m), and the preamplifier

ASE noise dominating at high values of m. Operation at the optimum bandwidth renders the channel

error probability to be a strong function of the optical bandwidth, thus providing motivation for the use